IMIS study

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The IMIS study ( I ntegrated M suntanned I nterplanetary S pace craft ) was one of Boeing on behalf of the NASA study conducted and published in January 1968 on the implementation of a manned Mars landing . The IMIS study is still one of the most detailed scenarios for an expedition to Mars.

genesis

In the mid-1960s, NASA was faced with the question of what goals American space travel should pursue after the moon landing and thus the end of the Apollo program. NASA administrator James E. Webb had authorized the Apollo application program (later renamed Skylab ) in December 1965, which envisaged the use of Apollo hardware for scientific missions in near-Earth space and for the construction of an embryonic space station. The NASA leadership assumed that, as the then director of today's Lyndon B. Johnson Space Center (then still called Manned Spacecraft Center (MSC)), Robert Gilruth , put it: NASA's manned space program “has other goals " need for a manned space flight goal other than" using Apollo hardware ".

Since the manned Mars landing was identified as a possible other target, the MSC North American Aviation commissioned a study to develop a Mars lander in August 1966 and NASA's Langley Research Center (LaRC) commissioned Boeing in November 1966 with the preparation of a study to build an interplanetary Spaceship. These two studies are combined as the IMIS study.

The spaceship

The IMIS study proposed a three-stage nuclear spaceship with nuclear-thermal propulsion. The drive consisted of five individual modules (Primary Propulsion Modules (PPM)).

  • 1 stage: 3 PPM for launch from Earth orbit
  • 2-stage: 1 PPM to brake into Mars orbit
  • 3-stage: 1 PPM for the return flight from Mars orbit

The PPM based on the NERVA reactor ( N uclear E ngine for R ocket V ehicle A pplication ), who was in development since the late fifties. Their dimensions were matched to a more powerful version of the Saturn V (Saturn V 25 S) with additional solid-state boosters .

The residential module (Mission Module (MM)) had four floors and a diameter of 6.61 meters. It should offer a crew of six 126 m² of living space.

A special module, the EEM (Earth Entry Module), was proposed for re-entry into the earth's atmosphere . In order to save the energy for braking the MM into orbit, its design has been optimized for high-speed re-entry into the earth's atmosphere. Besides the Mars Exploration Module (MEM), it was the only module that would have been specially developed for a Mars expedition.

The MEM

The MEM had the task of landing the crew on Mars, re-launching them into Mars orbit and serving as a residential unit during their stay on the surface of Mars. With its cone shape, it was externally similar to the Apollo command module , but was significantly larger (the base diameter would have been 9 meters as opposed to 3.90 meters for the command module). The cone shape was chosen because of the aerodynamic load on landing and take-off from Mars. The design was emphatically flexible, so that different versions could be derived from the basic concept that could supply groups of space travelers of different sizes for different lengths of time on the surface of Mars. The smallest configuration would have enabled two astronauts to spend four days on Mars, the largest four astronauts for 40 days. The weight of the MEM would have been between 30 and 50 tons, depending on the equipment. The IMIS study preferred a medium configuration as it envisaged a 30-day stay for three astronauts.

The expeditions

Various scenarios for manned Mars and Venus expeditions were examined within the study. Different departure times between 1975 and 1990 were examined, and a distinction was made between pure orbital and landing missions. All Venus flights were designed as orbital missions. As the most favorable scenarios for a Mars landing were opposition flights detected in 1981/82 or 1985/86 (depending on the time of release of funds). The number of expedition participants was set at six, three of whom were to land on Mars and stay there for 30 days. The total duration of the mission would have been 460 days.

Development and costs

Although some of the required systems were already being developed, the development time was estimated at at least ten years. The total cost including two Mars landings was given as 30 billion US dollars (1967). Of this, 4.3 billion (1967) alone went to the development of the MEM. The cost of each additional mission would have been about $ 2 billion (1967).

reception

The public reception of the study was divided. On the one hand, the timing of publication was unfortunate. With the widening Vietnam War , the US national budget was deeply in deficit, and it was clear that the expenditures initiated by President Lyndon B. Johnson to build a welfare state were not available for budget consolidation.

In addition, NASA's position was vulnerable in the spring of 1968 due to the delay of the Apollo program by more than a year and the death of the Apollo 1 astronauts. The size of the proposed spaceship, which is almost 180 meters long and weighs more than 1200 tons (the New York Times referred to it as 'Boeing's Behemoth') had a rather daunting effect on the public.

On the other hand, the cost analysis and the project plan of the IMIS study showed that a Mars landing was economically feasible (adjusted for inflation, the estimated costs were within the framework of the moon landing).

This was one reason why the manned Mars landing was one of the central points in the report published one and a half years later by the Space Task Group (The Post-Apollo Space Program: Directions for the Future) led by US Vice President Spiro Agnew .

The importance of the mission design defined in the IMIS study as the basis for many later studies for manned planetary missions is central .

literature

  • Kenneth Gateland, Philipp Bono; Frontiers of space; Macmillan 1968
  • David J. Shayler; Apollo the lost and forgotten missions; Springer 2002
  • David SF Portree; Humans to Mars - 50 Years of Mission Planning; Nasa Monographs of aerospace history 2001

Web links